package com.gt.utils;

import com.alibaba.fastjson.JSONObject;

import javax.crypto.Cipher;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.spec.GCMParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import java.io.IOException;
import java.security.GeneralSecurityException;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.util.Base64;

public class WxAPIV3AesUtil {
    static final int KEY_LENGTH_BYTE = 32;
    static final int TAG_LENGTH_BIT = 128;
//    private byte[] aesKey;

    /*public WxAPIV3AesUtil(byte[] key) {
        if (key.length != KEY_LENGTH_BYTE) {
            throw new IllegalArgumentException("无效的ApiV3Key，长度必须为32个字节");
        }
        this.aesKey = key;
    }*/

    public static JSONObject decryptToString(byte[] apiV3Key, byte[] associatedData, byte[] nonce, String ciphertext)
            throws GeneralSecurityException, IOException {
        try {
            if (apiV3Key.length != KEY_LENGTH_BYTE) {
                throw new IllegalArgumentException("无效的ApiV3Key，长度必须为32个字节");
            }
//            this.aesKey = apiV3Key;

            Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
            SecretKeySpec key = new SecretKeySpec(apiV3Key, "AES");
            GCMParameterSpec spec = new GCMParameterSpec(TAG_LENGTH_BIT, nonce);

            cipher.init(Cipher.DECRYPT_MODE, key, spec);
            cipher.updateAAD(associatedData);

            return JSONObject.parseObject(new String(cipher.doFinal(Base64.getDecoder().decode(ciphertext)), "utf-8"));
        } catch (NoSuchAlgorithmException | NoSuchPaddingException e) {
            throw new IllegalStateException(e);
        } catch (InvalidKeyException | InvalidAlgorithmParameterException e) {
            throw new IllegalArgumentException(e);
        }
    }

    /*public static void main(String[] args) {
        //解密回调信息
        byte[] key = SystemConst.WX_KEY.getBytes("UTF-8");
        WxAPIV3AesUtil aesUtil = new WxAPIV3AesUtil(key);
        String decryptToString = aesUtil.decryptToString(assc.getBytes("UTF-8"),noce.getBytes("UTF-8"),cip);
    }*/
}
